Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance as of at Dec. 31, 2011	$ 20	$ 227,577	$ 168,502	$ (2,266)	$ (805)	$ 393,028
Balance as of (in Shares) at Dec. 31, 2011	19,792,000			95,000
Net income			38,075			38,075
Other comprehensive income (loss)					(436)	(436)
Equity compensation		8,770				8,770
Exercise of stock options		78				78
Exercise of stock options (in Shares)	11,000
Issuance of shares pursuant to vesting of restricted stock units (in Shares)	231,000
Net payments for stock issuances and buybacks		33		(11,602)		(11,569)
Net payments for stock issuances and buybacks (in Shares)	(475,000)			517,000
Tax impact of stock option exercises and award vesting		804				804
Balance as of at Dec. 31, 2012	20	237,262	206,577	(13,868)	(1,241)	428,750
Balance as of (in Shares) at Dec. 31, 2012	19,559,000			612,000
Net income			39,330			39,330
Other comprehensive income (loss)					251	251
Equity compensation		8,786		105		8,891
Exercise of stock options	1	3,102				3,103
Exercise of stock options (in Shares)	159,000
Issuance of shares pursuant to vesting of restricted stock units (in Shares)	294,000			(5,000)
Net payments for stock issuances and buybacks		335		(7,782)		(7,447)
Net payments for stock issuances and buybacks (in Shares)	(247,000)			246,000
Tax impact of stock option exercises and award vesting		1,213				1,213
Balance as of at Dec. 31, 2013	21	250,698	245,907	(21,545)	(990)	474,091
Balance as of (in Shares) at Dec. 31, 2013	19,765,000			853,000
Net income			40,030			40,030
Other comprehensive income (loss)					(1,491)	(1,491)
Equity compensation		10,680		328		11,008
Exercise of stock options		1,831				1,831
Exercise of stock options (in Shares)	85,000
Issuance of shares pursuant to vesting of restricted stock units (in Shares)	333,000
Net payments for stock issuances and buybacks		454		(28,777)		(28,323)
Net payments for stock issuances and buybacks (in Shares)	(753,000)			753,000
Tax impact of stock option exercises and award vesting		3,543				3,543
Balance as of at Dec. 31, 2014	$ 21	$ 267,206	$ 285,937	$ (49,994)	$ (2,481)	$ 500,689
Balance as of (in Shares) at Dec. 31, 2014	19,430,000			1,606,000